首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   89568篇
  免费   3213篇
  国内免费   91篇
化学   55466篇
晶体学   432篇
力学   2279篇
综合类   1篇
数学   15722篇
物理学   18972篇
  2023年   644篇
  2022年   597篇
  2021年   995篇
  2020年   1259篇
  2019年   1179篇
  2018年   1770篇
  2017年   1515篇
  2016年   2954篇
  2015年   2559篇
  2014年   2570篇
  2013年   5566篇
  2012年   5787篇
  2011年   5778篇
  2010年   3623篇
  2009年   3026篇
  2008年   5007篇
  2007年   4856篇
  2006年   4339篇
  2005年   4200篇
  2004年   3665篇
  2003年   2959篇
  2002年   2611篇
  2001年   1751篇
  2000年   1620篇
  1999年   1151篇
  1998年   883篇
  1997年   774篇
  1996年   1009篇
  1995年   707篇
  1994年   804篇
  1993年   770篇
  1992年   807篇
  1991年   699篇
  1990年   716篇
  1989年   640篇
  1988年   597篇
  1987年   562篇
  1986年   528篇
  1985年   796篇
  1984年   725篇
  1983年   541篇
  1982年   640篇
  1981年   626篇
  1980年   527篇
  1979年   518篇
  1978年   512篇
  1976年   522篇
  1975年   454篇
  1974年   480篇
  1973年   477篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Development of biocompatible porous supports is a promising strategy in the field of tissue engineering for the repair and regeneration of bone tissues with severe damage. Graphene oxide aerogels (GOAs) are excellent candidates for the manufacture of these systems due to their porosity, ability to imitate bone structure, and mechanical resistance, and according to their surface chemical reactivity, they can facilitate osseointegration, osteogenesis, osteoinduction and osteoconduction. In this review, synthesis of GOAs from the most primary source is described, and recent studies on the use of these functionalized carbonaceous foams as scaffolding for bone tissue regeneration are presented.  相似文献   
32.
The synthesis and characterisation of a family of block codendrimers consisting of highly versatile mesogenic and carbazole‐containing 2,2‐bis(hydroxymethyl)propionic acid (bis‐MPA) dendrons are reported. The liquid‐crystal behaviour was investigated by means of differential scanning calorimetry, polarised‐light optical microscopy and X‐ray diffraction. Depending on the chemical structure of the constituent dendrons, the codendrimers show lamellar or columnar mesophases. On the basis of the experimental results, models both at the molecular level and in the mesophase are proposed. The physical properties of the block codendrimers derived from the presence of the carbazole moiety in their structure were investigated: photoluminescence in solution and in the mesophase, electrochemical behaviour and hole transport. Electrodeposition of carbazole dendrons afforded a globular supramolecular conformation in which the mesogenic molecular side plays a key role.  相似文献   
33.
34.
35.
36.
37.
38.
39.
40.
In this paper, we study the local linear convergence properties of a versatile class of Primal–Dual splitting methods for minimizing composite non-smooth convex optimization problems. Under the assumption that the non-smooth components of the problem are partly smooth relative to smooth manifolds, we present a unified local convergence analysis framework for these methods. More precisely, in our framework, we first show that (i) the sequences generated by Primal–Dual splitting methods identify a pair of primal and dual smooth manifolds in a finite number of iterations, and then (ii) enter a local linear convergence regime, which is characterized based on the structure of the underlying active smooth manifolds. We also show how our results for Primal–Dual splitting can be specialized to cover existing ones on Forward–Backward splitting and Douglas–Rachford splitting/ADMM (alternating direction methods of multipliers). Moreover, based on these obtained local convergence analysis result, several practical acceleration techniques are discussed. To exemplify the usefulness of the obtained result, we consider several concrete numerical experiments arising from fields including signal/image processing, inverse problems and machine learning. The demonstration not only verifies the local linear convergence behaviour of Primal–Dual splitting methods, but also the insights on how to accelerate them in practice.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号